Re: Radon flux from soils

[paul.l.ziemer.1@purdue.edu]

The effect of moisture on radon emanation from soils would 
probably exhibit the same patterns that have been reported for 
uranium tailings and flyash.  Strong and Levin (Health Phys, 42, 
27, 1982) demonstrated that for tailings, the emanation 
coefficient increased with moisture content up to a point.  
Likewise, Barton and Ziemer (Health Phys. 50, 581-588, 1986) 
found that for fly ash the emanation coefficient increased 
between 0 and 20 % moisture content, and then tended to decrease 
with higher moisture levels.  
The increase in emanation coefficient as a function of moisture 
content is best explained in terms of the recoil of the radon 
nucleus.  As moisture content increases, the fraction of recoil 
nuclei that terminate their paths in intraparticle pores or voids 
increases.  At some point, with increasing water content, the 
lower diffusion coefficient of radon in the interstitial water 
may become significant and overcome the contribution from the 
first phenonenon.
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E-mail: ziemer@purdue.edu

Paul L. Ziemer, Ph.D., C.H.P
Head, School of Health Sciences
Purdue University
W. Lafayette, IN 47907
Phone: 317-494-1435   FAX: 317-496-1377
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